Re: Shrinkit.Exe

[dempson@actrix.gen.nz (David Empson)]

Supertimer <supertimer@aol.com> wrote:

> Jerry Kindall <kindall@mail.manual.com> wrote:
> 
> >In any case, a file downloaded to a Mac that doesn't have a resource
> >fork will not magically have one added just because it's been on a Mac.
> >If that were the case, files copied from a Mac to a ProDOS disk would
> >always be useless to ProDOS 8 programs.  Obviously this isn't the case.
> >Just as on the Apple II, it is perfectly legal for Mac files to lack
> >resource forks.
> 
> It is the case unless you pass it through ProTYPE, which removes
> the forks.  I'm not sure which program does it.  Either Netscape or
> PC Exchange.  Somehow, the resource fork appears and messes
> everything up.

I did some experimentation with this a while ago, and have just repeated
it.  The primary culprit is PC Exchange, though other programs on the
Mac could make things worse by adding their own resources.

The rule is that the Mac will always copy a file to a ProDOS volume as
an extended file (hence inaccessible by ProDOS-8), _unless_ the file is
identifiable as a native ProDOS file.  This is required to preserve the
Macintosh Finder information, including the Mac type and creator.

A native ProDOS file is identified as follows:

1. Its Mac creator must be 'pdos'.

2. Its Mac file type may be 'TEXT' or either of the two encoded ProDOS
file type conventions:

(a) 'XY  ', where 'XY' is the ProDOS filetype as hexadecimal ASCII (e.g.
'FF  ' for a SYS file).  The auxiliary type is always zero in this case.

(b) 'pXYZ', where 'p' is a literal lower case 'p' ($70), 'X' is the
ProDOS filetype (in binary) and 'YZ' is the ProDOS auxiliary type (also
in binary).  For example, a NuFX (ShrinkIt) archive should have a ProDOS
filetype of $E0 and auxiliary type of $8002, which ends up encoded as
the following four bytes: $70 $E0 $80 $02.

A nominal ProDOS file will still end up as an extended file on the
ProDOS volume if it already has a resource fork.


ProType simply sets the filetype and creator codes to something
appropriate, so the file will not be unnecessarily saved as an extended
file when copied to the ProDOS volume.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand